1. Field of the Invention:
The present invention relates to a heat printing sheet which is used for printing a pattern or mark made of a hot melt ink composition by coating the melted hot melt composition (colored heat-meltable composition) on an intaglio roll having engraved pattern or mark and pressing a base of synthetic polymer film having a nonporous and flat surface and having high flexibility, with the coated intaglio roll. (plate cylinder). When the pattern or mark of the heat printing sheet is printed on the substrate, the heat printed sheet is heated, pressed or pressed under heating from the back surface of the heat printed sheet to print the pattern or mark on the substrate.
2. Description of the Prior Art:
Heretofore, solvent-type printing sheets and sublimatable-dye type printing sheets have been known as heat printing sheets. Solvent-type printing sheets are prepared by printing the desired pattern on a nonadhesive layer of a paper base by silk screen techniques or offset techniques and coating an adhesive layer on th printed substrate, to give three layers, the nonadhesive layer, the printed ink layer and the adhesive layer. These layers are respectively formed by coating each with solvent solutions. Accordingly, organic solvents are used in the steps of the production of the solvent-type printing sheet, the danger of firing and a pollution caused by vaporization of large amounts of the organic solvents can occur and the process is complicated because of the three steps. Moreover, since the adhesive layer is formed on the outer surface of the solvent-type printing sheet, a blocking sheet is placed between the adhesive layer and the back surface of other heat printing sheets in the pile which is inconvenient. On the other hand, the sublimatable dye-type printing sheet is prepared by printing a sublimatable dye so as to dye a fabric by the sublimation of the dye by heat-treatment. In the sublimation of the dye, the printing should be carried out at high temperatures, thus dyeability and heat-resistance of the fabric are required and only fabrics made of special fibers, such as polyester fibers, can be used as the substrate. The patterns printed by using the solvent-type printing sheet and the sublimatable dye-type printing sheet are flat and have no depth and lack continuous tone density.